The invention relates to an access control system by means of which the access to at least one space via at least one door can be controlled and which includes a transponder communication device adapted to provide contactless communication with at least one transponder which controls the authorization to access via the at least one door, and which includes at least two transmission coils each having a given receiving range, which coils are adapted to receive transponder signals which each contain at least one type of authorization information and which are connected to the transponder communication device which is capable of detecting identification information representative of at least a part of a received transponder signal, and which includes a first activation device which can be activated by an authorized person, which first activation device is associated with the first transmission coil and the first door and by means of which access to its associated first door can be initiated and which is connected to the transponder communication device, which is capable of generating first activation information representing the activated first activation device, and which includes at least one door opener which can be activated by means of the transponder communication device so as to open a door, and which includes a logic device by means of which the door opener of the first door can be activated upon receipt of identification information representing at least a part of a transponder signal received by the first transmission coil, and of first activation information.
The invention further relates to a product including an access control system, by means of which the access to at least one space in the product via at least one door can be controlled and which includes a transponder communication device adapted to provide contactless communication with at least one transponder which controls the authorization to access via the at least one door, and which includes at least two transmission coils each having a given receiving range, which coils are adapted to receive transponder signals which each contain at least one type of authorization information and which are connected to the transponder communication device which is capable of detecting identification information representative of at least a part of a received transponder signal, and which includes a first activation device which can be activated by an authorized person, which first activation device is associated with the first transmission coil and the first door and by means of which access to its associated first door can be initiated and which is connected to the transponder communication device, which is capable of generating first activation information representing the activated first activation device, and which includes at least one door opener which can be activated by means of the transponder communication device so as to open a door, and which includes a logic device by means of which the door opener of the first door can be activated upon receipt of identification information representing at least a part of a transponder signal received by the first transmission coil, and of first activation information.
Such an access control system of the type defined in the first paragraph and a product in the form of a motor vehicle of the type defined in the second paragraph are known from the magazine IEEE Transactions on Industrial Electronics, Vol. 35, No. 2, May 1988, pp. 208 to 216. The known motor vehicle including the known access control system, by means of which the access to the passenger compartment and the trunk of the known motor vehicle can be controlled, comprises two transmission coils, of which one transmission coil is associated with the driver's door of the motor vehicle and of which the other transmission coil is associated with the trunk of the motor vehicle. With respect to the two transmission coils it is to be noted that these coils have only a small receiving range situated inside a semicircle having a radius of approximately 70 cm, and that the transmission coil associated with the driver's door is arranged at the location of the driver's door handle and the other transmission coil associated with the trunk lid is arranged at the location of the rear bumper. The receiving ranges of the two transmission coils should not overlap one another, which requirement is met by the known motor vehicle. Moreover, this known motor vehicle including the known access control system has a driver's door switch near the driver's door handle and a trunk lid switch on the trunk lid, the driver's door switch forming a first activation device and the trunk lid switch forming a second activation device. Owing to the closely spaced arrangement of the one transmission coil and the driver's door switch forming the first activation device at the location of the driver's door handle and the closely spaced arrangement of the other transmission coil and the trunk lid switch forming the second activation device on or in the proximity of the trunk lid, it has been achieved that in the case that an authorized person, who carries a transponder which controls the access authorization by means of authorization information, i.e. by means of a code, actuates one of the switches provided as activation devices--after which a transponder signal containing authorization information is transmitted from the transponder to the transmission coil situated in the proximity of the actuated switch and from this coil to the transponder communication device and the authorization information is detected and evaluated as identification information in the transponder communication device--the motor vehicle door corresponding to the actuated switch is opened correctly.
However, in a comparatively large number of cases it is not possible, or only at a substantial expense, to arrange a transmission coil having only a small receiving range as closely as possible to the corresponding activation device of an access control system. It such cases the only possibility may be to arrange the transmission coil comparatively far from its associated activation device but, as a result of the small receiving range of such a transmission coil, this has the disadvantage that it requires a comparatively complicated manipulation or special precautions in order achieve at the same time activation of the activation device and transmission of a transponder signal containing authorization information from a transponder to the transmission coil associated with the activated activation device and thereby assure a correct opening of a door selected by an authorized person. Furthermore, it is to be noted with regard to the known motor vehicle including the known access control system that owing to the small receiving ranges of the transmission coils a separate transmission coil must be provided for each door of the motor vehicle. This involves additional expenditure with regard to material costs and, particularly, assembly costs, which is unfavorable.